Recording/reproducing systems for massive storage and retrieval of data are generally of two types. One type is a library type wherein the discs are stored in cartridges or protective casings and positioned on shelves for access by a take-out transfer mechanism. When one disc is to be accessed, the disc with cartridge is retrieved from the shelf location by the take-out/transfer mechanism and loaded into a recording/reproducing unit within the unit. The other type is a stack type wherein a plurality of discs are stacked on a common spindle and accessed by recording/reproducing heads provided for each of the recording faces of the discs. One or more heads are used in a stack type system for recording/reproducing data.
In the library type system, the recording/reproducing media is exchangeable. The shelves supporting the recording media, for example discs, are sealed to a certain extent against contamination by dust and other particles, but the extent of sealing is limited in order to enable prompt handling of the exchange of the discs. Dust contamination is not adequately prevented as a result. Since dust eventually adheres to the discs, cleaning is required to maintain a long service life of the system.
In order to overcome the dust contamination problem in the storage of discs in a library type system, it has been proposed, for example in Japanese patent laid-open application no. 276,056/1990, to house the recording medium transfer mechanism and the recording/reproducing unit in a sealed casing with the shelves of discs. This prevents dust from accumulating on the surfaces of the discs to a much greater extent than if the discs are housed in an unsealed casing.
In a stacked type system, the recording media are typically magnetic discs, such as hard discs. In a stacked type system using hard discs, the discs are completely sealed and therefore not exchangeable.
Although it is advantageous to enclose the discs in a sealed casing to minimize contamination from dust, the recording media is difficult to exchange. Thus, adding or exchanging recording media in both types of systems is difficult when the systems are enclosed in a sealed casing to prevent dust contamination.